A War-Prone Tribe Migrated out of Africa to Populate the World
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A war-prone tribe migrated out of Africa to populate the world. Eduardo Moreno1. 1 CNIO, Melchor Fernández Almagro, 3. Madrid 28029, Spain. Of the tribal hunter gatherers still in existence today, some lead lives of great violence, whereas other groups live in societies with no warfare and very little murder1,2,3,4,5. Here I find that hunter gatherers that belong to mitochondrial haplotypes L0, L1 and L2 do not have a culture of ritualized fights. In contrast to this, almost all L3 derived hunter gatherers have a more belligerent culture that includes ritualized fights such as wrestling, stick fights or headhunting expeditions. This appears to be independent of their environment, because ritualized fights occur in all climates, from the tropics to the arctic. There is also a correlation between mitochondrial haplotypes and warfare propensity or the use of murder and suicide to resolve conflicts. This, in the light of the “recent out of Africa” hypothesis”6,7, suggests that the tribe that left Africa 80.000 years ago performed ritualized fights. In contrast to the more pacific tradition of non-L3 foragers, it may also have had a tendency towards combat. The data implicate that the entire human population outside Africa is descended from only two closely related sub-branches of L3 that practiced ritual fighting and probably had a higher propensity towards warfare and the use of murder for conflict resolution. This may have crucially influenced the subsequent history of the world. There is little evidence for the practice of war before the late Paleolithic3,4. Of the many cave paintings from this period none depict people attacking other people and there is no archeological evidence of large scale fighting during this period of social evolution1,2,3,4,5. This has led to the hypothesis that the Paleolithic was a period of warlessness, grounded in low population density1,2. Moreover, the studies of African hunter gatherers such as the Mbuti and the Hadza led to the believe that hunter gatherers were pacific, because their migratory behavior permitted the resolution of conflicts merely by avoiding contact with potential enemies1,2. According to this view, the emergence of war would have been a Neolithic event caused by sedentary behaviors that prevented the resolution of conflict by migration of one of the conflicting groups or individuals. The emergence of agriculture during the Neolithic period would have also increased population densities, enhancing the probability of conflicts. Finally, it has been proposed that food surpluses produced by agriculture permitted the appearance of professional warriors and therefore the funding of wars for longer periods of time1,2. However, this hypothesis is contradicted by the existence of other hunter gatherer cultures such as Indian Americans, some tribes of South America, as well as New Guineans or Aborigines of Australia, all of them engaged in endemic warfare and frequently raiding neighboring groups to seize goods, women or territories5. This contrasting behavior has led to confusion regarding whether the hunter gatherer society leads to a pacific lifestyle or not1,5. Several studies have tried to address the question of what explains the different behavior of these tribes regarding their relative belligerency. For example, it has been argued that the emergence of a war-culture could be a consequence of the particular circumstances of the hunter gatherers, like for example a behavior derived from the need to protect their land from incoming tribes or resource scarcity and increased food competition1-5. Results and Discussion Here I have used genetic data such as the mitochondrial haplogroups of different tribes of hunter gatherers (Figure 1, Table 1), and have correlated them with cultural behaviors. In particular, to study the differences in war-prone behavior, I have studied the pattern of ritualized fights, archeological and ethnographical evidence for warfare, or the use of murder and suicide as a mean for conflict resolution among several tribes of modern hunter gatherers throughout the world. One possible caveat of this approach is that present day bellicose or peaceful behavior may not represent the ancestral state of hunter gatherers several thousand years ago. Although this is certainly a possibility8, several studies have indicated that there is a general correlation between genetic relatedness and linguistic or cultural similarity in Africa, suggesting that cultural inheritance is almost as stable as genetic inheritance. For example, a recent genome- wide study of a set of diverse Africans revealed the presence of 14 genetically distinct ancestral population clusters in Africa9. Interestingly, each cluster consisted of populations that shared genetic similarity, as well as cultural and/or linguistic properties (for example Khoesan- speaking hunter-gatherers, Bantu-speakers, Cushitic-speakers, etc). This supports the view that, although some exceptions occur, genetics and culture correlate. And, moreover, that ancestral populations were culturally and geographically structured before modern humans migrated out of Africa6. Therefore, assuming that genetic ancestry is a good indication of cultural ancestry, which could be the oldest hunter gatherer behavior in Africa? Current paleontological data suggest that modern humans appeared in sub-Saharan Africa 200,000 years ago10,11. Moreover, mtDNA, X and Y-chromosome studies and Genome-wide data have indicated higher levels of genetic diversity in Africans compared to non-Africans, as expected if first humans appeared in Africa6,9,12,13,14,15. Therefore, African hunter gatherers seem a reasonable starting point to study the evolution of warfare. Among the African foragers, the Ju/´hoansi or !Kung16,17,18,19 of the Kalahari desert in South Africa, Botswana and Namibia have been shown to carry the most basal mitochondrial DNA haplogroup20, L0 (Figure 1, Table 1), and are therefore the best choice as being considered an ancestral state with regards to belligerent behavior. !Kung do not gather for ritual fights (Figure 2) and prefer dance and storytelling as pastimes. Among the !Kung murder and suicide are also uncommon (Figure 3) and conflicts are normally eased with humor or avoiding contact. However, some physical fights do occur. Finally, although the !Kung are generally a peaceful society they can resort to war in order to defend their territory (Figure 4) and there is evidence that this has also been happening in the past, because there are rock paintings depicting !Kung bushmen fighting. In general !Kung men proud themselves of being good hunters16,17,18,19. Before the migration out of Africa, three main lines of Homo sapiens diverged from the !Kung line20: bearers of mitochondrial haplogroup L1 (mtDNA) / A (Y-DNA), bearers of haplogroup L2 (mtDNA) / B (Y-DNA), and carriers of haplogroup L3 (mtDNA). African hunter gatherers that correspond to the mitochondrial haplogroup L1 are several groups of pygmies like the Aka and Efé from Congo, the Baka from Cameroon and the Hadza from Tanzania16,20,21(Figure 2). Consistent with their genetic relatedness, they also share many cultural similarities. For example, their ritual gatherings revolve around storytelling, music, hunting and dancing and there are no ritual fights involved. Also little murder and violence is involved in their relationship with their neighbors (Figure 3) and in all cases they rather have peaceful commercial relationships with neighboring pastoralist tribes such as the Bantu. Moreover, unlike the !Kung, there is no archeological nor ethnographical evidence of war (Figure 4). It seems that in case of conflict all L1 mtDNA bearers choose to move apart rather than to fight16,20,21. African hunter gatherers that correspond to the mitochondrial haplogroup L2 are the Mbuti from Congo16,20,21(Figure 1). They also form a pacific society with no archeological nor ethnographical evidence of war and where conflicts are ridiculed and jokes used to alleviate tensions. Again, their ritual gatherings involve music, storytelling and dancing, without ritual fights (Figures 2-4). And their wives value their men as long as they consider them good hunters. Finally, descendants of the mitochondrial haplogroup L3 constitute the vast majority of hunter gatherers all over the world22(Figure 1, Table 1). The reason for this is that, according to the Recent African Origin model of modern human origins, anatomically modern humans that evolved in Africa, migrated to Eurasia and Oceania within the last 80000 years22,23,24,25 and then migrated to the Americas within the last 30000 years26. The geographic expansion of a small number of anatomically modern humans out of Africa resulted in a population bottleneck. For example, based on mtDNA studies it has been proposed that all non Africans belong to one tiny African branch, bearers of haplotypes M and N, which are closely related in an L3 sub- branch6,20,22, meaning that the entire human population outside of Africa is descended from only two closely related sub-branches of L36,22. Two main migratory routes out of Africa have been hypothesized for anatomically modern humans. One model involves a northern route of migration via North Africa and the Nile valley into the Levant with subsequent dispersal into both Europe and Asia 27. Alternatively, a later southern coastal route has been proposed in which modern humans left Africa by crossing the Bab-el-Mandeb strait at the mouth of the Red Sea and then rapidly migrated along the South Asia coastline to Australia/Melanesia where evidence of human settlement dating to around 60000 years ago can be found 28,29. Strong support for an East African origin of migration of modern humans has been provided by a recent genetic study that correlated levels of microsatellite diversity and the geographic position of sampled populations inferred a waypoint of dispersal of anatomically modern humans out of Africa centered on the Red Sea9. Although this study was not able to rule out the possibility of multiple migrations out of Africa, prior analysis of autosomal haplotype variability suggests that migration events originating from multiple genetically distinct source populations in Africa are unlikely30.